forked from quic-go/quic-go
/
byteorder_little_endian.go
157 lines (140 loc) · 3.81 KB
/
byteorder_little_endian.go
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package utils
import (
"bytes"
"fmt"
"io"
)
// LittleEndian is the little-endian implementation of ByteOrder.
var LittleEndian ByteOrder = littleEndian{}
type littleEndian struct{}
var _ ByteOrder = &littleEndian{}
// ReadUintN reads N bytes
func (littleEndian) ReadUintN(b io.ByteReader, length uint8) (uint64, error) {
var res uint64
for i := uint8(0); i < length; i++ {
bt, err := b.ReadByte()
if err != nil {
return 0, err
}
res ^= uint64(bt) << (i * 8)
}
return res, nil
}
// ReadUint64 reads a uint64
func (littleEndian) ReadUint64(b io.ByteReader) (uint64, error) {
var b1, b2, b3, b4, b5, b6, b7, b8 uint8
var err error
if b1, err = b.ReadByte(); err != nil {
return 0, err
}
if b2, err = b.ReadByte(); err != nil {
return 0, err
}
if b3, err = b.ReadByte(); err != nil {
return 0, err
}
if b4, err = b.ReadByte(); err != nil {
return 0, err
}
if b5, err = b.ReadByte(); err != nil {
return 0, err
}
if b6, err = b.ReadByte(); err != nil {
return 0, err
}
if b7, err = b.ReadByte(); err != nil {
return 0, err
}
if b8, err = b.ReadByte(); err != nil {
return 0, err
}
return uint64(b1) + uint64(b2)<<8 + uint64(b3)<<16 + uint64(b4)<<24 + uint64(b5)<<32 + uint64(b6)<<40 + uint64(b7)<<48 + uint64(b8)<<56, nil
}
// ReadUint32 reads a uint32
func (littleEndian) ReadUint32(b io.ByteReader) (uint32, error) {
var b1, b2, b3, b4 uint8
var err error
if b1, err = b.ReadByte(); err != nil {
return 0, err
}
if b2, err = b.ReadByte(); err != nil {
return 0, err
}
if b3, err = b.ReadByte(); err != nil {
return 0, err
}
if b4, err = b.ReadByte(); err != nil {
return 0, err
}
return uint32(b1) + uint32(b2)<<8 + uint32(b3)<<16 + uint32(b4)<<24, nil
}
// ReadUint16 reads a uint16
func (littleEndian) ReadUint16(b io.ByteReader) (uint16, error) {
var b1, b2 uint8
var err error
if b1, err = b.ReadByte(); err != nil {
return 0, err
}
if b2, err = b.ReadByte(); err != nil {
return 0, err
}
return uint16(b1) + uint16(b2)<<8, nil
}
// WriteUint64 writes a uint64
func (littleEndian) WriteUint64(b *bytes.Buffer, i uint64) {
b.Write([]byte{
uint8(i), uint8(i >> 8), uint8(i >> 16), uint8(i >> 24),
uint8(i >> 32), uint8(i >> 40), uint8(i >> 48), uint8(i >> 56),
})
}
// WriteUint56 writes 56 bit of a uint64
func (littleEndian) WriteUint56(b *bytes.Buffer, i uint64) {
if i >= (1 << 56) {
panic(fmt.Sprintf("%#x doesn't fit into 56 bits", i))
}
b.Write([]byte{
uint8(i), uint8(i >> 8), uint8(i >> 16), uint8(i >> 24),
uint8(i >> 32), uint8(i >> 40), uint8(i >> 48),
})
}
// WriteUint48 writes 48 bit of a uint64
func (littleEndian) WriteUint48(b *bytes.Buffer, i uint64) {
if i >= (1 << 48) {
panic(fmt.Sprintf("%#x doesn't fit into 48 bits", i))
}
b.Write([]byte{
uint8(i), uint8(i >> 8), uint8(i >> 16), uint8(i >> 24),
uint8(i >> 32), uint8(i >> 40),
})
}
// WriteUint40 writes 40 bit of a uint64
func (littleEndian) WriteUint40(b *bytes.Buffer, i uint64) {
if i >= (1 << 40) {
panic(fmt.Sprintf("%#x doesn't fit into 40 bits", i))
}
b.Write([]byte{
uint8(i), uint8(i >> 8), uint8(i >> 16),
uint8(i >> 24), uint8(i >> 32),
})
}
// WriteUint32 writes a uint32
func (littleEndian) WriteUint32(b *bytes.Buffer, i uint32) {
b.Write([]byte{uint8(i), uint8(i >> 8), uint8(i >> 16), uint8(i >> 24)})
}
// WriteUint24 writes 24 bit of a uint32
func (littleEndian) WriteUint24(b *bytes.Buffer, i uint32) {
if i >= (1 << 24) {
panic(fmt.Sprintf("%#x doesn't fit into 24 bits", i))
}
b.Write([]byte{uint8(i), uint8(i >> 8), uint8(i >> 16)})
}
// WriteUint16 writes a uint16
func (littleEndian) WriteUint16(b *bytes.Buffer, i uint16) {
b.Write([]byte{uint8(i), uint8(i >> 8)})
}
func (l littleEndian) ReadUfloat16(b io.ByteReader) (uint64, error) {
return readUfloat16(b, l)
}
func (l littleEndian) WriteUfloat16(b *bytes.Buffer, val uint64) {
writeUfloat16(b, l, val)
}